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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 129
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Hard, wear-resistant coatings of thin film borides based on AlMgB14 have the potential to be applied industrially to improve the tool life of cutting tools and pump vanes and may account for several million dollars in savings as a result of reduced wear on these parts. Past work with this material has shown that it can have a hardness of up to 45GPa and be fabricated into thin films with a similar hardness using pulsed laser deposition. These films have already been shown to be promising for industrial applications. Cutting tools coated with AlMgB14 used to mill titanium alloys have been shown to substantially reduce the wear on the cutting tool and extend its cutting life. However, little research into the thin film fabrication process using pulsed laser deposition to make AlMgB14 has been conducted. In this work, research was conducted into methods to optimize the deposition parameters for the AlMgB14 films. Processing methods to eliminate large particles on the surface of the AlMgB14 films, produce films that were at least 1m thick, reduce the surface roughness of the films, and improve the adhesion of the thin films were investigated. Use of a femtosecond laser source rather than a nanosecond laser source was found to be effective in eliminating large particles considered detrimental to wear reduction properties from the films. Films produced with the femtosecond laser were also found to be deposited at a rate 100 times faster than those produced with the nanosecond laser. However, films produced with the femtosecond laser developed a relatively high RMS surface roughness around 55nm. Attempts to decrease the surface roughness were largely unsuccessful. Neither increasing the surface temperature of the substrate during deposition nor using a double pulse to ablate the material was found to be extremely successful to reduce the surface roughness. Finally, the adhesion of the thin films to M2 tool steel substrates, assessed using the Rockwell C indentation adhesion test, was found to be substantially improved by the deposition of a titanium interlayer, but unaffected by increasing the temperature of the substrates. The titanium was found to improve the adhesion strength of the films because it reacted with both the steel and the AlMgB14 compound to form new compounds. Ultimately, it was concluded that the films with the best properties were produced with a femtosecond pulsed laser and were deposited on top of a titanium interlayer to improve the thin film adhesion.
Author: Michael Joseph Stock
Publisher:
ISBN:
Category :
Languages : en
Pages : 102
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Procedural variables such as fluence, polarization, pulse width, machining speed, and material properties are investigated to determine their effects on the PLD and laser micromachining of aluminum magnesium boride. In this work, a 120-fs pulsed, 800-nm wavelength Ti: Sapphire laser was used for micromachining thin films of ultra-hard AlMgB14 and polysilicon thin films on silicon substrate. Polysilicon was first deposited by low-pressure chemical vapor deposition followed by boride using femtosecond pulsed laser deposition. Channels were then machined in thin films to pattern a device that would produce a linear resistance/deflection curve. Results show that the ultrafast laser has precisely ablated the thin films. However, the high-energy fluence used in single-pass surface micromachining enabled the formation of recast layer of molten silicon substrate ejected by vapor pressure, and conglomerates of re-condensed material at a distance from the feature. Multi-pass surface micromachining at low energy fluences eliminated the recast layers and produced clean features. Ultrafast laser micromachining is certainly beneficial over wet and dry etching in reproducibility, material choice, and minimal number of processing steps. Thin films of ultra-hard AlMgB14 were grown on Si (100) substrates at 300 K using femtosecond pulsed Ti:sapphire laser and subsequently annealed in argon gas up to 1373 K for two hours. X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscope, and nanoindentation were employed to study the composition, microstructure and hardness of thin films. Results were compared with nanosecond pulsed KrF excimer laser-deposited films. The as-deposited and post-annealed films (up to 1173 K), independent of the pulse width, exhibited amorphous structures with a hardness of 40 GPa. However, post-annealing at higher temperatures has varied effects on crystallization depending on the pulse width. The effect of pulse width on the microstructure and quality of thin films is discussed.
Author: Yoosuf N. Picard
Publisher:
ISBN:
Category :
Languages : en
Pages : 422
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 129
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Book Description
Hard, wear-resistant coatings of thin film borides based on AlMgB14 have the potential to be applied industrially to improve the tool life of cutting tools and pump vanes and may account for several million dollars in savings as a result of reduced wear on these parts. Past work with this material has shown that it can have a hardness of up to 45GPa and be fabricated into thin films with a similar hardness using pulsed laser deposition. These films have already been shown to be promising for industrial applications. Cutting tools coated with AlMgB14 used to mill titanium alloys have been shown to substantially reduce the wear on the cutting tool and extend its cutting life. However, little research into the thin film fabrication process using pulsed laser deposition to make AlMgB14 has been conducted. In this work, research was conducted into methods to optimize the deposition parameters for the AlMgB14 films. Processing methods to eliminate large particles on the surface of the AlMgB14 films, produce films that were at least 1m thick, reduce the surface roughness of the films, and improve the adhesion of the thin films were investigated. Use of a femtosecond laser source rather than a nanosecond laser source was found to be effective in eliminating large particles considered detrimental to wear reduction properties from the films. Films produced with the femtosecond laser were also found to be deposited at a rate 100 times faster than those produced with the nanosecond laser. However, films produced with the femtosecond laser developed a relatively high RMS surface roughness around 55nm. Attempts to decrease the surface roughness were largely unsuccessful. Neither increasing the surface temperature of the substrate during deposition nor using a double pulse to ablate the material was found to be extremely successful to reduce the surface roughness. Finally, the adhesion of the thin films to M2 tool steel substrates, assessed using the Rockwell C indentation adhesion test, was found to be substantially improved by the deposition of a titanium interlayer, but unaffected by increasing the temperature of the substrates. The titanium was found to improve the adhesion strength of the films because it reacted with both the steel and the AlMgB14 compound to form new compounds. Ultimately, it was concluded that the films with the best properties were produced with a femtosecond pulsed laser and were deposited on top of a titanium interlayer to improve the thin film adhesion.
Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 924
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Author: Krishna Harsha Puppala
Publisher:
ISBN:
Category : Molybdenum oxides
Languages : en
Pages : 120
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Pulsed Laser Deposition (PLD) technique, with its vast tunability in terms of thin film fabrication has been the center of this study. By changing the temporal component of the laser source used for deposition into the femtosecond (fs) regime, interesting structural, morphological changes can be achieved which may prove to be beneficial for photocatalytic applications. In particular, molybdenum oxide thin films, which are the less well-studied and potentially newer candidates for photocatalysis applications have been chosen for investigation. Hence, a detailed characterization study of molybdenum oxide thin films synthesized using femtosecond-based (f-PLD) and nanosecond-based (n-PLD) techniques, was carried out in terms of their structural, morphological, surface chemical/ electronic states and vibrational properties using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The f-PLD technique was found to produce more favorable molybdenum oxide thin films deposited on glass for surface-related applications, in terms of having a higher surface to volume ratio, than the n-PLD technique. A related simultaneous study of substrate-based effect on the thin films produced using n-PLD system, also revealed both variation among the morphological, structural, and electronic (in terms of Mo oxidation state) properties depending upon the nature of the substrate used to synthesize the molybdenum oxide thin films. Special cases of thin films on epitaxial substrates (Si, sapphire) have been characterized to determine the parameters necessary for fabricating highly-textured thin films with large surface-area to volume ratio, which is key to efficient photo-catalysts.
Author: Theodore T. Pekny
Publisher:
ISBN:
Category :
Languages : en
Pages : 138
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Author:
Publisher: Academic Press
ISBN: 0123743966
Category : Science
Languages : en
Pages : 2785
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Book Description
From the Introduction: Nanotechnology and its underpinning sciences are progressing with unprecedented rapidity. With technical advances in a variety of nanoscale fabrication and manipulation technologies, the whole topical area is maturing into a vibrant field that is generating new scientific research and a burgeoning range of commercial applications, with an annual market already at the trillion dollar threshold. The means of fabricating and controlling matter on the nanoscale afford striking and unprecedented opportunities to exploit a variety of exotic phenomena such as quantum, nanophotonic and nanoelectromechanical effects. Moreover, researchers are elucidating new perspectives on the electronic and optical properties of matter because of the way that nanoscale materials bridge the disparate theories describing molecules and bulk matter. Surface phenomena also gain a greatly increased significance; even the well-known link between chemical reactivity and surface-to-volume ratio becomes a major determinant of physical properties, when it operates over nanoscale dimensions. Against this background, this comprehensive work is designed to address the need for a dynamic, authoritative and readily accessible source of information, capturing the full breadth of the subject. Its six volumes, covering a broad spectrum of disciplines including material sciences, chemistry, physics and life sciences, have been written and edited by an outstanding team of international experts. Addressing an extensive, cross-disciplinary audience, each chapter aims to cover key developments in a scholarly, readable and critical style, providing an indispensible first point of entry to the literature for scientists and technologists from interdisciplinary fields. The work focuses on the major classes of nanomaterials in terms of their synthesis, structure and applications, reviewing nanomaterials and their respective technologies in well-structured and comprehensive articles with extensive cross-references. It has been a constant surprise and delight to have found, amongst the rapidly escalating number who work in nanoscience and technology, so many highly esteemed authors willing to contribute. Sharing our anticipation of a major addition to the literature, they have also captured the excitement of the field itself in each carefully crafted chapter. Along with our painstaking and meticulous volume editors, full credit for the success of this enterprise must go to these individuals, together with our thanks for (largely) adhering to the given deadlines. Lastly, we record our sincere thanks and appreciation for the skills and professionalism of the numerous Elsevier staff who have been involved in this project, notably Fiona Geraghty, Megan Palmer and Greg Harris, and especially Donna De Weerd-Wilson who has steered it through from its inception. We have greatly enjoyed working with them all, as we have with each other.
Author: Xiaojuan Huang
Publisher:
ISBN:
Category :
Languages : en
Pages : 176
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Author: Chunlei Guo
Publisher: CRC Press
ISBN: 1315310848
Category : Technology & Engineering
Languages : en
Pages : 359
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Book Description
This comprehensive handbook gives a fully updated guide to lasers and laser technologies, including the complete range of their technical applications. This third volume covers modern applications in engineering and technology, including all new and updated case studies spanning telecommunications and data storage to medicine, optical measurement, defense and security, nanomaterials processing and characterization. Key Features: • Offers a complete update of the original, bestselling work, including many brand-new chapters. • Deepens the introduction to fundamentals, from laser design and fabrication to host matrices for solid-state lasers, energy level diagrams, hosting materials, dopant energy levels, and lasers based on nonlinear effects. • Covers new laser types, including quantum cascade lasers, silicon-based lasers, titanium sapphire lasers, terahertz lasers, bismuth-doped fiber lasers, and diode-pumped alkali lasers. • Discusses the latest applications, e.g., lasers in microscopy, high-speed imaging, attosecond metrology, 3D printing, optical atomic clocks, time-resolved spectroscopy, polarization and profile measurements, pulse measurements, and laser-induced fluorescence detection. • Adds new sections on laser materials processing, laser spectroscopy, lasers in imaging, lasers in environmental sciences, and lasers in communications. This handbook is the ideal companion for scientists, engineers, and students working with lasers, including those in optics, electrical engineering, physics, chemistry, biomedicine, and other relevant areas.
Author: Iowa State University
Publisher:
ISBN:
Category : Commencement ceremonies
Languages : en
Pages : 562
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